Anatomy and Biomechanics of the Posterior Cruciate Ligament and Posterolateral Corner

The knowledge and understanding of the anatomy and biomechanical function of the posterior cruciate ligament (PCL) and posterolateral corner (PLC) of the knee is vitally important when evaluating injury and considering reconstruction. The PCL and the PLC both have important roles to play in the stability of the knee. Through numerous experimental designs, the biomechanical roles of the PCL and PLC have been clarified. The PCL's most well-defined role is as a primary restraint and stabilizer to posterior stress. It appears that this role is greatest at higher degrees of knee flexion. The natural history of a PCL deficiency leads to increased contact pressures and degeneration of both the medial and patellofemoral compartments. The PLC is a restraint to posterior translation, posterolateral rotation, external rotation, and varus loads. It is important to recognize a PLC injury before cruciate ligament reconstruction, as a failure to diagnose may lead to subsequent graft rupture. Poor surgical outcomes after PCL reconstruction have been attributed to many factors, the most common of which include the following: additional intra-articular pathology, poor fixation methods, insufficient knowledge of PCL or PLC anatomy leading to improper tunnel placement, and poor surgical candidates. In this article, we attempt to provide a framework for understanding the anatomy and biomechanics of the PCL and PLC and their surgical implications.